1. Technical Field
The present invention relates to optical communications, and more particularly to polarization mode dispersion (PMD) compensation in multilevel coded-modulation schemes using a BLAST algorithm and iterative polarization cancellation.
2. Description of the Related Art
The bit-error ratio (BER) performance of fiber-optic communication systems operating at high data rates is degraded by intra-channel and inter-channel fiber nonlinearities, polarization mode dispersion (PMD), and chromatic dispersion. In order to overcome those challenges, novel advanced techniques and devices in modulation and detection, coding and signal processing are required.
These and other drawbacks and disadvantages of the prior art are addressed by the present principles, which are directed to polarization mode dispersion (PMD) compensation in multilevel coded-modulation schemes using a BLAST algorithm and iterative polarization cancellation.
According to an aspect of the present principles, there is provided a receiver. The receiver includes a vertical Bell Laboratories Layered Space-Time Architecture (V-BLAST) orthogonal frequency division multiplexing (OFDM) detector configured to receive input sequences and partially cancel polarization interference with respect to the input sequences to output symbol estimates for the input sequences. The receiver further includes one or more low-density parity-check (LDPC) decoders coupled to the V-BLAST OFDM detector configured to receive channel bit reliabilities and output code words. The channel bit reliabilities are indirectly calculated from the symbol estimates. The one or more LDPC decoders iteratively provide extrinsic soft information feedback to the V-BLAST OFDM detector to compensate for the polarization interference.
According to another aspect of the present principles, there is provided a receiver. The receiver includes an iterative detector configured to receive input sequences and iteratively and partially cancel polarization interference with respect to the input sequences to output symbol estimates for the input sequences. The receiver further includes one or more low-density parity-check (LDPC) decoders coupled to the iterative detector configured to receive channel bit probabilities from the iterative detector and output code words. The channel bit reliabilities are indirectly calculated from the symbol estimates. The one or more LDPC decoders iteratively provide extrinsic soft information feedback to the iterative detector to compensate for the polarization interference.
According to yet another aspect of the present principles, there is provided a method. The method includes receiving and sampling an input signal using a sampler. The method further includes partially cancelling polarization interference using a vertical Bell Laboratories Layered Space-Time Architecture (V-BLAST) orthogonal frequency division multiplexing (OFDM) detector configured to receive channel samples of the input signal and provide symbol estimates. The method also includes decoding the input signal based on channel bit reliabilities to output code words using one or more low-density parity-check (LDPC) decoders. The channel bit reliabilities are indirectly calculated from the symbol estimates. The method additionally includes iteratively feeding back extrinsic soft information to the V-BLAST OFDM detector to compensate for the polarization interference.
According to still another aspect of the present principles, there is provided a method. The method includes receiving and sampling an input signal using a sampler. The method further includes partially cancelling polarization interference using an iterative detector configured to receive channel samples of the input signal and provide symbol estimates. The method also includes decoding the input signal based on channel bit reliabilities to output code words using one or more low-density parity-check (LDPC) decoders. The channel bit reliabilities are indirectly calculated from the symbol estimates. The method additionally includes iteratively feeding back extrinsic soft information to the iterative detector to compensate for the polarization interference.
These and other features and advantages will become apparent from the following detailed description of illustrative embodiments thereof, which is to be read in connection with the accompanying drawings.